Modern communication standards and systems use a carrier aggregation mode for enhancing the bandwidth of the data transfer. Carrier aggregation mode means operating in a first communication system including transmitting and receiving data or other signals and at least receiving signals in another communication system or in another band. Carrier aggregation interoperability or functionality needs to be incorporated in modern devices. International standards are defining a couple of band combinations that may be used for carrier aggregation mode operation. Some of these band combinations cause problems and need additional filtering to attenuate a certain harmonic mode of a frequency, the harmonic mode appearing in the second band of the band combination and producing noise signals. However, additional filtering usually causes additional losses, which is not desirable.